I got the same idea after speaking with some WebOS application developers and studying how WebOS applications work a bit. There are some nice aspects and as long as you do the basic & supported stuff (thing shopping lists, twitter clients, RSS readers, simple encyclopedias) everything is alright.

But when you want to do some more advanced stuff - games, editors, terminal emulators, painting programs, video players - you either can't (all graphic intensive games on WebOS actually use SDL, not the Enyo or Mojo frameworks) or have to use horrible hacks. On of the devs mentioned writing a painting program - you can't access files directly from the HTML framework. He had to create a system service, serialize the bitmap to some plaintext xml message (yeah, really "<data>101010111010</data>) and send it to the service, which finally saved it as a file in storage.

Like this, it can be actually more difficult because of jumping through all the needless hops than just doing it the native way.